How do I leave when I love him

I think I want to leave my bf of 5 years. I fantasize about a different life and I wait around till he’s sleeping or away from me to think about a happier life with someone else and maybe sometimes him, but a different him acting the way I would like. I love him but I know it’s over cause I’m looking for escapes in doing these things… but with that being said. We’ve been together 5 years and for 2-3 I’ve been posting on glow tracking this absurd behaviors of his and I’ve recently come to realize he is pretty narcissistic and EXTREEMEEEELY emotionally abusive. For example he will ignore me for making simple errors and mistakes, and then twist it around on me. He nitpicks me and makes every mistake a lesson and makes sure no mistake gets swept under the rug. I have been open and mature about how I hate being nitpicked but he continues to do it and then flips the fact that I have a reaction to his nitpicking around on me. For example, I apparently put the Brita water filter in the fridge backwards because of the handle being the other way so he litetally takes time out of his day to ask me why it’s backwards, and calls me lazy bc I can’t just put it in correctly, and then he sits there and he can’t stop talking until I give him an explanation. It’s just the stupidest quality about him because he ignores all conflict and stonewalls to the max.

I have my doubts but I want therapy to be our last option. We are 25 and 22 and sex is once a month or less and 90% of the time on his terms. No sexy talk, no making out, or any intimacy in between sex either. Just sex once a month is our only gathering in the bedroom. He’s obsessed with video games, every night he’s playing and knows our schedules differ and doesn’t chose to prioritize me, though these are all things he used to do, I don’t think I’m asking for much. Sex once a month is what I’ve been dealing with for about two years, it’s been on a steady decline and we used to have sex daily when we first got together. He says we stopped having sex because I’m mean… when I know I’ve been mean but it’s because I’ve told him I’m going to break up with him if things don’t change and he doesn’t do ANYTHING TO CHANGE. Now he’s using that as his new excuse.. I don’t get it. We’ve been living together and have a dog and I believe he’s gotten too comfortable with me but then again he’s such a manipulator and I wish he would see it, because I love him and sometimes things are good. And I’m really not sure if he knows how he is, but me telling him should be enough.. when is it truly over? Is it worth waiting for him to agree to therapy. I need help I can’t keep doing this to myself every time I get an opportunity to think. I wanna be happy